1. Field of the Invention
The present invention relates generally to wireless energy harvesting methods and systems. Specifically, the preferred embodiments of the present invention relate to the integration of antennas and electronics for harvesting ubiquitous electromagnetic energy, transforming that energy into useful power, and storing such power for usage.
2. Description of the Related Art
Typically, energy harvesting techniques and systems are focused on renewable energy such as solar energy, wind energy, and wave action energy from moving water. Solar energy is harvested by arrays of solar cells that convert radiant energy to DC power. Such energy is limited in low-light conditions. Cumbersome wind turbines that convert wind energy to electrical power depend on sufficient wind to spin the blades of the turbines to generate power. Wave action energy is harvested by water turbines or other apparatuses that are capable of converting the energy in the moving water into electrical power. This energy conversion is typically performed at complex hydroelectric power plants or by mechanical/electrical conversion apparatuses, such as those shown in U.S. Pat. Nos. 5,842,838 and 6,045,339 to Berg.
Another approach to energy harvesting is wireless power transmission via focused microwave signals. Unlike the above renewable energy technologies which harvest energy from natural sources, electrical energy of the wireless power transmission technology is remotely harvested and converted from focused microwave signals that are transmitted by a constructed source. For example, U.S. Pat. No. 5,043,739 to Logan et al. discloses a high frequency rectenna device for rectifying electromagnetic energy at microwave frequencies and higher and converting the energy into direct-current (DC) power to conduct wireless power transmission. Applications of this disclosure are focused on high-energy microwave radiation and high temperatures. One such application includes sending power to satellites or high altitude devices from the earth by electromagnetic waves. Another application involves collecting solar power from large space-based arrays of solar cells and transmitting the energy via electromagnetic waves to earth. A third application involves the direct conversion of microwaves generated by fusion reactions into a direct current.